Creating Fluffy Mini Sponge Cakes can be a straightforward process if you follow these easy steps:

1. Preheat your Oven: Preheat your oven to 350°F (175°C). Prepare muffin tins by greasing them or lining with paper liners.
2. Separate Eggs: In a bowl, separate the egg whites from the yolks. Place the egg whites in a clean bowl for whipping.
3. Whip Egg Yolks: In a separate bowl, whisk the egg yolks with granulated sugar until the mixture is pale and creamy.
4. Add Flavor: Stir in the vanilla extract, then set the mixture aside.
5. Whip Egg Whites: Using an electric mixer, whip the egg whites in a clean bowl until stiff peaks form. This step is crucial for achieving that fluffy texture.
6. Combine Mixtures: Gently fold the egg yolk mixture into the whipped egg whites, being careful not to deflate the volume.
7. Add Dry Ingredients: Sift in the flour, baking powder, and salt. Carefully intermingle these dry ingredients until no streaks remain.
8. Incorporate Butter: If desired, fold in the melted butter for added richness, but this is optional.
9. Fill Muffin Tins: Spoon the batter into the prepared muffin tins. Fill each cup about two-thirds full.
10. Bake: Place the tins in the oven and bake for 15-20 minutes, or until a toothpick inserted into the center comes out clean.
11. Cool: Once baked, remove them from the oven and allow them to cool in the pan for about 10 minutes before transferring them to wire racks.

These steps will help you achieve impeccable Fluffy Mini Sponge Cakes every time!